1. Field of the Invention
The present invention relates to an iron type golf club set which can obtain the longest carry in each number of irons while maintaining a durability.
2. Description of the Related Art
For example, Japanese Unexamined Patent Publication No. 2001-29523 discloses, as shown in FIG. 12, an iron type head “a” constituted by a face plate “b” forming a main portion hitting a ball, and a head main body “c” supporting the face plate “b”. The face plate “b” is formed by using a metal material, having a small specific gravity, such as titanium or titanium alloy, and the head main body “c” is formed by using a metal material, having a greater specific gravity than the face plate “b”, such as stainless steel. The head main body “c” is provided, for example, with an opening portion O, and is provided with a face receiving portion supporting a peripheral edge portion of the face plate “b” around the opening portion O. Accordingly, a free deflecting area “d” which is not supported to the head main body “c” is formed in a center portion of the face plate “b”.
The head “a” has a low position of center of gravity and a large depth of center of gravity. Accordingly, the head reduces a probability of miss shot, and a beginner can easily hit a ball with the head. In this case, a plurality of iron type golf clubs are normally brought together and used as a set. The respective clubs in the set are different in a shaft length, a loft angle, a lie angle and the like. In particular, the shaft length is greater and the lie angle is smaller, in accordance with the club in the smaller number having the smaller loft angle. In accordance with the property of the club, a normal armature golfer tends to hit the ball on a toe side of a hitting face in accordance with the club in the smaller number, and inversely tends to hit the ball on a heel side of the hitting face in accordance with the club in the larger number.
As a result of researches of the present inventors, the conventional head includes a head in which a sweet spot is set in conformity with a hitting position of an armature golfer. However, in order to obtain the longest carry in each number of the iron, it is necessary to effectively position a thin portion “d1” having a good repulsion against the ball at the hitting point of the golfer.